1. Technical Field
The invention relates to backlight modules and light guide plates, and particularly to a light guide plate and a backlight module typically used in a liquid crystal display.
2. Description of Related Art
Currently, because liquid crystal displays (LCDs) are thin, lightweight, long lasting, and consume little power, they are extensively used in a variety of electronic devices. However, LCDs are not self-luminescent, therefore, backlight modules are typically required. Generally, backlight modules can be categorized as either direct-type backlight modules or edge-type backlight modules. Because direct-type backlight modules can provide high illumination in comparison with edge-type backlight modules, direct-type backlight modules are more widely employed in numerous applications.
Referring to FIG. 1, a conventional direct-type backlight module 2 includes a reflection plate 21, a plurality of LED packages 22, a light guide plate 23, and a diffusion plate 24. The LED packages 22 are disposed on the reflection plate 21. In addition, each of the LED packages 22 includes a reflective layer 221 disposed thereon. The light guide plate 23 is disposed above and is spaced apart from the reflective layer 221a predetermined distance. The light guide plate 23 includes a light output surface 231 that faces the diffusion plate 24. The diffusion plate 24 is disposed above and is spaced apart from the light guide plate 23 a predetermined distance.
Light emitted from an LED of each LED package 22 is reflected by the reflective layer 221 and the reflection plate 21 in succession to be redirected into the light guide plate 23. The light guide plate 23 allows the light from all the LED packages 22 to be redistributed, and guides the light to exit from the light output surface 231. The diffusion plate 24 is configured to emit the light uniformly to the display panel of an associated LCD device.
The predetermined distance between the reflective layer 221 and the light guide plate 23 is required to provide uniform illumination. This means reducing the volume of the LCD device for compact applications is difficult. Moreover, because the light is reflected by both the reflective layer 221 and the reflection plate 21, light energy is lost. This can make operation of the LCD device inefficient.
What is needed, therefore, is a light guide plate and a direct-type backlight module with same which are suitable for compact applications and which provide improved efficiency.